Apparatus and method for the installation of a pre-assembled stator core

ABSTRACT

The present invention comprises a method and apparatus for installing a stator core, or portions thereof, into a power generator frame  2  that comprises assembling the stator core inside of a container  60 , and then moving the container to the power generator  1 . The container  60  is horizontally aligned with the power generator  1 , and the stator core is transferred from the container to the power generator.

CROSS-REFERENCE TO RELATED APPLICATIONS

This invention claims priority to U.S. Provisional application60/565,307 entitled Methods and Apparatuses for Assembling GeneratorStator Cores, which is incorporated herein by reference. This inventionis further related to US applications: Method and Apparatus of theMounting of and Circumferential Displacement of Radial Forces in aStator Core Assembly, by Sargeant et al.; Horizontal Assembly of StatorCore using Keybar Extensions, by Sargeant et al.; Horizontal Assembly ofStator Core using a Central Rail Structure by Majernik et al.; all filedherewith and all incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to power generators, and more specificallystator cores. More particularly, the invention relates to the transferof a pre-assembled stator core into stator frame.

BACKGROUND

The generator stator core is the largest single component in the trainof a turbine generator set. The stator cores are generally manufacturedfrom thousands of laminations of relatively thin steel plates which arestacked, pressed and clamped together into the large cylindrical form ofthe stator core. The clamping is necessary to accommodate variations inthickness of the stock steel plate laminations, commonly referred to ascrowns. Improperly clamped laminations can result in plate vibrationduring generator operation, which results from magnetic impulses or coreelliptical dilation.

Typically, the stator core is assembled from the steel plates directlyat the final installation site. However, the large size of the statorcore and the need for proper clamping results in stator coremanufacturing difficulties, including generous floor space and highcrane requirements. The manufacture of stator cores via the traditionalmethods result in manufacturing lead time and other associatedmanufacturing difficulties. For example, if the core is stacked directlyin the stator frame, the frame must be delivered to the site before anymanufacturing steps can occur. Additionally, intermediate core pressingequipment is needed to press and clamp the steel plates together atincremental lengths. If, on the other hand, the stator core ismanufactured in an external fixture, the external fixture itself adds tothe manufacturing costs and requires additional floor space on site andstill requires the use of heavy cranes.

U.S. Pat. No. 5,875,540 by Sargeant, which is incorporated herein byreference, overcame some of the problems with the prior art by firstassembling a number of laminations into a distinct set, referred to as adonut, and then stacking these donuts to form a stator core. This savedgreat amounts of time over assembling the laminations individually, andproduced a stator core with less flaws.

When the individual laminations, or the set of laminations in a donut,are installed into a core, they engage what are referred to as keybars.Keybars are essentially rods that run the internal length of the statorcore and provide a hook-in spot for the laminations. FIG. 1 illustratesa stator frame that is empty of any laminations. The keybars 6 run theinternal length of the stator frame 2, and are generally attached to theframe through stator support rings 4.

The size of laminations and resulting stator core can vary, but atypical stator core lamination has a weight of 3.6 lbs (1.6 kg). Theresults in a weight per inch of core of 1530 lbs/in (1740 kg/cm). For acore length of 225 inches (563 cm), the total weight will beapproximately 344,250 lbs (156,477 kg).

In the prior art, when generators need their cores replaced, the onlyway to accomplish this has been to strip out the old core and thenre-stack the new core lamination by lamination. Since the generators arelarge, immobile objects, each lamination needs to be horizontallyinserted into position by hand. This is a very time consuming effort,which requires that the generator be off-line for long periods of time.What is needed is a better way of adding a new core to an existinggenerator frame.

SUMMARY OF THE INVENTION

With the foregoing in mind, methods and apparatuses consistent with thepresent invention facilitate the placement of assembled stator coresinto existing generator frames. Typically when a stator core needs to beinstalled into a stator frame, each lamination needs to be stacked intoposition individually. This is a time consuming process, which is proneto causing imperfections in the stacking of the stator core. The presentinvention reduces these problems by providing a container that holds apre-assembled stator core.

The pre-assembled core is shipped to the stator frame in the container.The stator core is then transferred to the stator frame by aligning thecontainer with the stator frame and sliding the core into position. Thismethod and apparatus may also be used on partially assembled statorcores, and segments of stator cores referred to as donuts. Thelaminations may be assembled within the container itself, or assembledoutside of the container and then inserted into it.

These and other objects, features, and advantages in accordance with thepresent invention are provided in one embodiment by a method ofinstalling a stator core in a power generator that comprises assemblingthe stator core inside of a container, and then moving the container tothe power generator. The container is horizontally aligned with thepower generator, and the stator core is transferred from the containerto the power generator.

In another particular embodiment, partial stator cores are divided intomultiple shipping containers. In a related embodiment, the multipleshipping containers are horizontally aligned at both ends of a statorframe, and the stator core is assembled from both ends of the statorframe.

In another embodiment, the present invention provides for an apparatusfor the horizontal placement of a stator core within a stator frame.This apparatus comprises a container, and the container comprises aninternal space capable of holding the stator core, and multiple keybarsarraigned along the internal space capable of securing the stator corewithin the internal space. The container is capable of being alignedwith a stator frame and the stator core that is disposed within thecontainer is horizontally transferable to the stator frame.

In a particular embodiment, the apparatus further comprises keybarextensions, where the keybar extensions bridge the container and thestator frame. In another particular embodiment a central rail structureis provided, where the central rail structure is capable of supportingand aiding in the movement of at least one of laminations, donuts and astator core within the container. In a related embodiment, the apparatusfurther comprises both a central rail structure and keybar extensions.

In a particular embodiment, the apparatus further comprises supportrings, where the support rings are capable of applying a radial force tothe multiple keybars. In another particular embodiment, the apparatusfurther comprises external hooking members for aiding in the transportof the container. In still another particular embodiment donuts andstator cores are capable of being assembled within the container.

BRIEF DESCRIPTION OF THE FIGURES

The invention is explained in more detail by way of example withreference to the following drawings:

FIG. 1 illustrates a typical stator frame with keybars that has not hadthe stator core yet assembled.

FIG. 2 illustrates a container according to one embodiment of thepresent invention.

FIG. 3 illustrates a container being aligned with an existing powergenerator in accordance with one embodiment of the present invention.

FIG. 4 illustrates the horizontal transfer of a fully assembled statorcore from a container to an existing power generator in accordance withone embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides for a method and apparatus for theplacement of a pre-assembled stator core into a stator frame using acontainer. The pre-assembled stator core may be fully or partiallyassembled, and the stator frame may be new, or part of a pre-existingpower generator. The present invention will also function with statorcore segments, referred to as donuts.

A stator core comprises a plurality of stacked laminations. To build astator core, the laminations need to be stacked within a stator frame,and then secured into position by a variety of techniques. Wherepossible, the stator core is assembled vertically, so that gravity canbe used to aid in stacking the core. Additionally, it has been foundthat pre-assembling some laminations into lamination groups, calleddonuts, also aids in the stacking of the stator core. It is not alwayspossible, however, to assemble a stator core vertically. For example,existing power generators need to have their stator cores periodicallyreplaced. The old core is removed and the new core needs to be stackedhorizontally, since the pre-existing stator frame is immobile. This isan extremely time consuming effort that causes the power generator to beoff-line for extended periods of time.

The present invention allows for a new stator core, either partially orfully assembled, to be shipped to the desired location. The containerthat the stator core is shipped in provides a support structure similarto a stator frame. When on location, the container is aligned with theexisting stator frame, and the stator core is slid from the containerinto the stator frame. The entire stator core may be transferred in thismanner, or sections of the core may be transferred at a time. Thepartially assembled core is either contained within a single container,or optionally contained within multiple containers. When the new statorcore comprises multiple donuts divided into multiple containers, thecontainers may be placed on either side of a stator frame so that thenew stator core may be assembled from both sides at the same time.

Since having existing power generators off-line is wasteful ofresources, stator cores can be placed into the containers ahead of time.The pre-assembled core can then be sent to the desired location beforethe old core is removed, saving vast amounts of time. In this manner,power generators may be modernized more easily as well. In the past,operators have been reluctant to replace old cores with newer, moreefficient cores since such a replacement would mean that the powergenerators would be off-line for an extended period of time. The presentinvention greatly reduced potential down-time, making suchmodernizations feasible. Although the present invention is ideallysuited for the replacement of old stator cores in pre-existing powergenerators, it is equally applicable for the assembly of new powergenerators as well.

When stator cores are assembled horizontally, quality is difficult tomaintain. This is due to the difficulty of placing the large number ofunwieldy laminations properly into position. However, with the presentinvention, the core is either fully or partially pre-assembled,improving the quality of the new stator core.

The pre-assembled core, whether fully pre-assembled or pre-assembledinto sectional donuts, can be stacked either inside of or outside of thecontainer. Since the container is mobile, the laminations can be stackedwithin the container vertically. It may still, however, be desired tostack the stator core outside of the container, and then transfer it tothe container for transportation to the stator frame location.

The container may be aligned by a variety of techniques. For example, avertical flange on the end of a generator where the bearing brackets arebolted on would have a mating flange on the container that could bebolted to the vertical flange on the generator. Other examples includemarkings on the container, instruments and other types of physicalguides.

For example, a cable is attached to the stator core that would runthrough the frame to a turning block on the opposite side. An overheadwould be used to pull on the cable and the stator core. Other methodsinclude a push-pull arrangement, that can be done either manually orhydraulically. The push-pull arrangement can use the aid of a beam orother type of physical device. Further, the push-pull arrangement can bean integral part of the container design

As illustrated in FIG. 1, a standard stator frame 2 comprises supportrings 4 and keybars 6. The keybars 6 engage the outer periphery of thelaminations, helping to hold them in position. In FIG. 2, one embodimentof a container 60 is shown. The container 60 holds a pre-assembledstator core or portions thereof. Similar to a stator frame, thecontainer has a mechanism for supporting the stator core, in thisembodiment it is support rings 4 and keybars 6. The container 60 mayalso have end cover panels (not shown) and access panels 62. The accesspanels 62 can be used to check on the status of the stator core within,and/or to aid in the stacking to the stator core. The container may alsohave hooks or handles 64 to aid in the lifting or tilting of thecontainer.

Once the stator core, or a portion thereof, is assembled or partiallyassembled within the container, the entire container is aligned with apower generator, as shown in FIG. 3. In the embodiment shown, acontainer 60 containing a fully assembled stator core is aligned with anexisting power generator 1. The container 60 is secured against thegenerator 1 forming a tight seem 61. Preferably the two are furtherconnected by physical means, such as screws, hooks, dove-tailing,temporary welds and similar techniques.

Referring to FIG. 4, the transfer of a fully assembled stator core 66 isillustrated. The core 66 is slid laterally 68 along the keybars 6 in thecontainer 60. The core 66 then engages the keybars 6 in the stator frame2. Once the stator core 66 is fully within the stator frame 2, thecontainer 60 can be removed.

Advantageous to a fully assembled stator core 66 include that windings69 and other core components can be pre-assembled with the rest of thecore. However, the present invention is also applicable to partiallyassembled stator cores. The core may be partially assembled within asingle container, or may be divided into multiple containers.

The transfer of the core, or portions thereof, from the container to thenew stator frame may be accomplished by a variety of techniques. Two ofthese techniques are detailed in patent applications Horizontal Assemblyof Stator Core using Keybar Extensions, by Sargeant et al., andHorizontal Assembly of Stator Core using a Central Rail Structure byMajernik et al., which are incorporated herein by reference. Theseapplications teach methods and apparatus of using central railstructures and keybar extensions to transfer and place laminations anddonuts. The central rail structure and the keybar extensions, eitherindependently or in conjunction, may be used with the present invention.

Additionally, the related patent application Method and Apparatus forthe Mounting of and Circumferential Displacement of Radial Forces in aStator Core Assembly, by Sargeant et al., which is incorporated hereinby reference, teaches the used of expanded grooves in laminations foraccepting keybars, and using certain wedges in the expanded grooves tocircumferentially displace radial forces from guard rings. The expandedgrooves in use with the present invention will facilitate the transferof the core from the container to the new stator frame. Slide pads,disclosed in the related application, will also facilitate the transferof the core

In one embodiment the present invention provides for a method ofinstalling a stator core in a power generator that comprises assemblingthe stator core inside of a container, and then moving the container tothe power generator. The container is horizontally aligned with thepower generator, and the stator core is transferred from the containerto the power generator.

In a related embodiment, the stator core is assembled vertically insideof the container. This may be done in a remote location, or on-site. Inone embodiment the assembled core is a replacement core, and in anotherembodiment it is an original core for a power generator. In a differentembodiment, the container is used to remove an old stator core, and thesame or similar container is used to install the replacement core.

In a particular embodiment, the container has access panels. In anotherembodiment the container has support rings, end covers, and externalhooking members. Support rings apply radial force to the keybars insideof the container, forcing the keybars more securely into the laminationsinside. End covers protect and contain the core while shipping. Thecontainer is also provided with external hooking members. These allowfor the container to be more easily shipped.

In another embodiment, stator cores are assembled outside of thecontainer, and then placed inside for shipping to the power generator.In another embodiment of the present invention, partial stator cores areinstalled or assembled inside of the container. Partial stator coresrefer to anything less and a complete stator core, and includelaminations and donuts. A stator core refers to a stator core that has acomplete allotment of laminations. A fully assembled stator core refersto a stator core that has additional elements assembled, such aswindings.

In another particular embodiment, partial stator cores are divided intomultiple shipping containers. In a related embodiment, the multipleshipping containers are horizontally aligned at both ends of a statorframe, and the stator core is assembled from both ends of the statorframe.

In another embodiment keybar extensions provide support for stator coresand/or partial stator cores as they are transferred from the containerto the stator frame. In another embodiment a central rail structureproves support for stator cores and/or partial stator cores as they aretransferred from the container to the stator frame. In a relatedembodiments both keybar extensions and a central rail structure areused.

In another embodiment, the present invention provides for an apparatusfor the horizontal placement of a stator core within a stator frame.This apparatus comprises a container. The container comprises aninternal space capable of holding the stator core, and multiple keybarsarraigned along the internal space capable of securing the stator corewithin the internal space. The container is capable of being alignedwith a stator frame and the stator core that is disposed within thecontainer is horizontally transferable to the stator frame.

In a particular embodiment, the apparatus further comprises keybarextensions, where the keybar extensions bridge the container and thestator frame. In another particular embodiment a central rail structureis provided, where the central rail structure is capable of supportingand aiding in the movement of at least one of laminations, donuts and astator core within the container. In a related embodiment, the apparatusfurther comprises both a central rail structure and keybar extensions.

In a particular embodiment, the apparatus further comprises supportrings, where the support rings are capable of applying a radial pressureto the multiple keybars. In another particular embodiment, the apparatusfurther comprises external hooking members for aiding in the transportof the container. In still another particular embodiment donuts andstator cores are capable of being assembled within the container.

In another particular embodiment the apparatus is capable of receiving astator core horizontally from a stator frame. In another embodiment theapparatus is capable of receiving partial stator cores from a statorframe.

Though the present invention is discussed in primarily in terms of usein stator core, the invention is not limited to this, and other areas ofart may also benefit. Some of these other areas include, installation ofother components such as rotors and end-winding cones.

While specific embodiments of the invention have been described indetail, it will be appreciated by those skilled in the art that variousmodifications and alternatives to those details could be developed inlight of the overall teachings of the disclosure. Accordingly, theparticular arrangements disclosed are meant to be illustrative only andnot limiting as to the scope of the inventions which, is to be given thefull breadth of the claims appended and any and all equivalents thereof.

1. A method of installing a stator core in a power generator comprising:assembling said stator core inside of a container; moving said containerto said power generator; horizontally aligning said container with saidpower generator; and transferring said stator core from said containerto said power generator.
 2. The method of claim 1, wherein theassembling of said stator core inside of said container is performedvertically.
 3. The method of claim 1, wherein the aligning of saidcontainer is indicated by at least one of markings on said container,instruments on said container, and physical guides on said container. 4.The method of claim 1, wherein said container comprises access panels.5. The method of claim 1, wherein said container comprises end coveringsthat are removed during the installation of said stator core into saidpower generator.
 6. A method of installing a stator core in a powergenerator comprising: installing at least a portion of a stator coreinside of a container; moving said container to said power generator;horizontally aligning said container with said power generator; andtransferring said portion of a stator core from said container to saidpower generator.
 7. The method of claim 6, wherein said portion of astator core is a donut.
 8. The method of claim 7, wherein a plurality ofsaid containers are used to install said stator core.
 9. The method ofclaim 8, wherein said stator core is installed from both ends of saidpower generator.
 10. The method of claim 6, wherein said portion of astator core is a fully assembled stator core.
 11. The method of claim 6,wherein said portion of a stator core is assembled inside of saidcontainer.
 12. The method of claim 6, further comprising providingkeybar extensions, where said keybar extensions provide support to saidportion of a stator core while said portion of a stator core is beingmoved.
 13. The method of claim 6, further comprising providing a centralrail structure, where said central rail structure provides support tosaid portion of a stator core while said portion of a stator core isbeing moved.
 14. An apparatus for the horizontal placement of a statorcore within a stator frame, comprising: a container, wherein saidcontainer comprises: an internal space capable of holding said statorcore; a plurality of keybars arraigned along said internal space capableof securing said stator core within said internal space; wherein saidcontainer is capable of being aligned with a stator frame and saidstator core being disposed within said container is horizontallytransferable to said stator frame.
 15. The apparatus of claim 14,further comprising keybar extensions, wherein said keybar extensionsbridge said container and said stator frame.
 16. The apparatus of claim14, further comprising a central rail structure, wherein said centralrail structure is capable of supporting and aiding in the movement of atleast one of laminations, donuts and a stator core within saidcontainer.
 17. The apparatus of claim 14, further comprising supportrings, wherein said support rings are capable of applying a radialpressure to said plurality of keybars.
 18. The apparatus of claim 14,further comprising a powered transferring mechanism that is capable ofaiding the transfer of said stator core.
 19. The apparatus of claim 14,wherein at least one of donuts and stator cores are capable of beingassembled within said container.
 20. The apparatus of claim 14, whereina stator core being disposed within said stator frame is horizontallytransferable to said container.